Our feedback is as follows:
We understand the Rules Committee’s decision to consider resemblance on a case-by-case basis. However, we feel – regardless of the consequences for the particular design of tow post that provoked the original enquiry – that this is an unsatisfactory outcome. The word ‘resemble’ is not a sound basis for the determination of whether a component is notifiable.
We would like to suggest the following amendment to TR-4.16. We note that the conditions in (a) need to be carefully defined, and while they may not yet be perfect we hope that a refined version of this will help determine whether a component shall be counted in the applicable limits according to TR-4.4.
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4.16 A component shall be counted in the applicable limits regardless of whether that component satisfies
the specific Rules controlling its parameters in the Class Rules. In the event that a test component cannot
readily be identified as a specific component type, then its classification of type and quantity shall be determined by the Rules Committee by following the interpretation process detailed in Rule 7.5. In considering a potential component’s status as a specific, notifiable component the Rules Committee shall:
(a) determine that an item has at least the functions listed in the table below, in order to be considered as a component of that type;
Component Minimum required function to qualify as a specific component
Hull surfaces Can provide most of the buoyancy when the boat is floating and stationary and support the crew
Foil arm stocks Can transfer load from a foil wing to a hull
Foil wings Can generate hydrodynamic loads and transfer them into a beam connected to a hull
Foil flaps Can change the hydrodynamic load generated by a foil wing in a controlled manner
Rudders Can change the yaw moment for the hull
Mast tubes Can transfer aerodynamic loads generated by the mainsail and/or jib skins to the hull
Mainsail skins Can generate aerodynamic load and transfer it to the mast tube
Jib skins Can generate aerodynamic load and transfer it to the mast tube and hull
If (a) is satisfied then the Rules Committee shall determine whether or not a component is notifiable. In making the determination the Rules Committee shall consider:
(i) the properties that the component shares with the forms and functions of an AC75 Class Yacht component;
(ii) that the component need not match the overall functionality of an AC75 Class Yacht component; and
(iii) that in an extreme case, a single test component may be ruled as comprising multiple declared components if it is effectively serving the purpose of multiple components, depending on its method
of installation in a yacht. For example, a double‐ended rudder that could be installed either way
up, with only one half of the component tested at a time, could be ruled as two declared rudders.
However, a conventional rudder that could be installed at different extensions, or an asymmetric
foil wing with different design concepts on either side of its connection to a foil arm shall be treated
as a single component.
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RULE ENQUIRY #025 – Instrument Post
DRAFT INTERPRETATION
The Rules committee notes that in addition to the statements made in the original enquiry, TR-4.16(b) also states that “test components shall be counted even if they only resemble one aspect of an AC75 Class Yacht component, without matching the overall functionality...”
In this case, the towing post need only resemble one (or more) aspects of either the form or function of a mast tube (TR-4.16(a)). An instrumented towing post on an LEQ12, with its base mounted on the mast ball, introducing load through the mast ball and further supported by other rigging terminations at the very least partly resembles some aspects of a mast tube and is therefore captured under TR-4.1.
The Rules Committee considers 75-1.4, requiring that yachts be propelled by sails only, and that the instrumented towing post cannot hoist sails, as irrelevant in this context.
The Rules Committee considers that in the case of TR-4.16, resemblance should be determined on a case-by-case basis.
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Interpretation Request – TR-7.5(a)
Rule References:
A. TR-4.1
B. TR-4.4
C. TR-4.16
D. 75-1.4
Background
1. TR-4.1 restricts the use of a number of listed, key components of an LEQ12 yacht. Any component that “serves or partly serves the purpose of a listed component” shall be limited by these restrictions. The listed components and the number that’s allowed are set by TR-4.4 and they include the mast tube.
2. TR-4.16 requires that all listed ‘components shall be classified according to resemblance in form or function to AC75 Class Yacht components, whatever their scale’.
3. Rule 75-1.4 requires the AC-75 Class Yacht to ‘be propelled by sails only’ and so we assume that all components should be evaluated in their resemblance to an AC75 Class Yacht component used to propel the yacht with sails.
Question:
1. Please consider an instrumented towing post on an LEQ12, with its base fixed to the mast ball and further supported by other rigging terminations. The instrumented towing post can not be used and will not be used to hoist sails.
Is this instrumented towing post a mast tube for the purposes of TR-4.1?
Yes.
If the answer is yes, could the Rules Committee please explain what features lead to an instrumented towing post being interpreted as a mast tube? See above